The present invention, in some embodiments thereof, relates the use of decellularized extracellular matrix for encapsulating cells.
Cell encapsulation, a strategy whereby a pool of live cells is entrapped within a semipermeable membrane, represents an evolving branch of biotechnology and regenerative medicine.
Cell capsules are intended to protect the entrapped cell/tissue fragments against the components of the host immune system, while simultaneously permitting the unhindered passage of nutrients, oxygen and secreted therapeutics factors, allowing for the controlled delivery of therapeutic products to specific physiological sites in order to restore lost function due to disease or degeneration.
Since cells are capable of secreting therapeutics such as hormones or biological proteins in response to an external stimulus they may be used as therapeutics in the treatment of a myriad of diseases including endocrine disorders (diabetes, hypoparathyroidism) central nervous system disorders (Parkinson's and Alzheimer's), as well as conditions such as heart disease, and cancer. Further, cells may be engineered so as to express useful proteins, thereby increasing the range of diseases for which they may be used as therapeutics.
Alginates are a family of unbranched anionic polysaccharides derived from brown algae (Phaeophyta) which occur extracellularly and intracellularly at approximately 20% to 40% of the dry weight. The 1,4-linked α-1-guluronate (G) and β-d-mannuronate (M) are arranged in homopolymeric (GGG blocks and MMM blocks) or heteropolymeric block structures (MGM blocks). Cell walls of brown algae also contain 5% to 20% of fucoidan, a branched polysaccharide sulphate ester with 1-fucose four-sulfate blocks as the major component. Commercial alginates are often extracted from algae washed ashore, and their properties depend on the harvesting and extraction processes.
Alginate has been employed for encapsulating cells to be transplanted, since it is biocompatible both with host and with enclosed cells; moreover, its quality can be constantly ensured. Furthermore, the use of alginate ensures that the surface of the capsules is not rough thereby preventing the elicitation of immunological reactions when implanted.
Decellularized extracellular cell matrix (which comprises molecules such as the collagen family (as a major macromolecule), elastic fibers, glycosoaminoglycans (GAG) and proteoglycans, and adhesive glycoproteins) has also been proposed to fabricate capsules for cell encapsulation. The decellularized extracellular cell matrix serves as a network supporting the attachment and proliferation of cells.
Generation of decellularized ECM from natural tissues involves subjecting the tissues to enzymatic cellular digestion (e.g., using trypsin), hypotonic, hypertonic and/or low ionic strength buffers, detergent and chemical digestion (e.g., using SDS, Triton-X-100, ammonium hydroxide, peracetic acid) and non-micellar amphipatic molecules such as polyethylene glycole (PEG) (See for example, U.S. Pat. Appl. Nos. 20040076657, 20030014126, 20020114845, 20050191281, 20050256588 and U.S. Pat. Nos. 6,933,103, 6,743,574, 6,734,018, 5,855,620; and WO2006/095342 which are fully incorporated herein by reference).
Freytes et al., Biomaterials 29 (2008) 1630-1637 teaches a method of generating soluble, decellularized ECM and preparation of gels therefrom.
U.S. Patent Application No. 20120156250 teaches soluble decellularized ECM.
U.S. Patent Application No. 201000267143 teaches a scaffold of decellularized extracellular matrix and alginate.
U.S. Patent Application Nos. 20100189760 and 20100172942 teach a multilayered capsule for cell encapsulation, wherein at least one of the layers comprises alginate.
Mazzitelli et al., Acta Biomaterialia 7 (2011) 1050-1062 teaches cell encapsulating particles comprising decellularized ECM and alginate.